扫描全息术中菲涅耳波带板的衍射问题分析

对扫描全息术中作为编码孔径的菲涅耳波带板的衍射问题进行了数值计算和实验观测。对波带板的菲涅耳衍射积分方程进行了数值求解，在计算时考虑了透镜的位相调制作用；为了使分析问题直观、数值计算简化，通过对比有透镜时波带板的衍射强度分布，求解出无透镜时具有相同分布的等效距离，同时引入了菲涅耳虚衍射面的概念；为了定量描述波带板的衍射效应，定义了临界衍射距离；为了验证数值计算的正确性，在实验中观测并记录了透镜焦距、波带板环数和半径对临界衍射距离的影响；对发散球面波入射时临界衍射距离的变化也进行了讨论。数值计算和实验观测结果对波带板扫描全息成像系统中编码孔径的结构设计、成像物体与透镜的距离以及透镜焦距的选取具有指导意义。

Analysis of Fresnel-zone-plate Diffraction in Scanning Holography

In order to improve the resolving power of a scanning holographic system,the diffraction of a Fresnel-zone-plate(FZP) functioning as a coding aperture was studied.In consideration of the lens as a phase modulator,the integral diffraction equation of the FZP was solved digitally.As compared with the distribution of the diffraction intensity with and without a lens,an equivalent distance was introduced to simplify the analyses and a virtual Fresnel diffraction plane was proposed accordingly.Meanwhile,a critic...